Document handling apparatus



De- 18, 1962 R. E. MERSEREAU Erm. 3,069,157

DOCUMENT HANDLING APPARATUS 4 Sheets-Sheet 1 Filed Sept. 27, 1960 WmaDOCUMENT HANDLING APPARATUS Filed Sept. 27, 1960 4 Sheets-Sheet 2 i2 i42 54 v# wm 216 jy 50. llll mmuunE/-:i'lnungSsuul; Imm zza limi" i2 5 INV EN TORS um Robert Merereau I 56 BY dola A Capanna mmmwmwo.

De 18, 1962 R. E. MERsERl-:Au ETAL 3,069,157

DOCUMENT HANDLING APPARATUS Filed sept. 27, 1960 4 Sheets-Sheet 3 I'i gI 128. Hdalf'a A. dpa/ma BLLNM www@ Dec. 18, 1962 R. E, MERSEREAU ETAL3,069,157

DOCUMENT HANDLING APPARATUS Filed Sept. 27, 1960 .4 Sheets-Sheet 4 ITiff 5 I' 1 Il -144 l ./52

I M, 77W. Q l f77 f /75 1.9.3 .x78 E, f "0 i v 784 ./98 16% 5 Ei:- I 2041.90 200 FET-.- g3 V; i 206 A '/a /f 0 /58 146 :Il f3.2

A y M- www www@ United States Patent Office 3,069,157 DOCUMENT HANDLINGAPPARATUS Robert E. Mersereau, Rowayton, and Adolfo A. Capanna,Stamford, Conn., assignors to Pitney-Bowes, inc., Stamford, Conn., acorporation of Delaware Filed Sept. 27, 1960, Ser. No. 58,666 6 Claims.(Cl. 271-28) This invention relates to -apparatus for advancing a stackof documents toward a feeding location at which the documents aresuccessively fed from the stack, and more particularly, to such anapparatus including means for regulating the advance of the stack ofdocuments.

In many cases, the advance of a stack of documents toward such a feedinglocation must be regulated to ensure that the stack is advancedsufciently to bring the foremost letter of the stack to the properposition to be fed from the stack, while also ensuring that the stack isnot overly advanced, for example, to the point that the vforemost letteris jammed at the feeding location. Regulation of the advance of thestack of documents must be carried out to accommodate, for example,variations in the rate of feeding from the stack, variations in thedocument thickness from one stack to another and from document todocument of a single stack, and variations in the compactness of eachrespective stack.- By way of illustration, it will be clear that if the`document thickness varies from document to document of a stack, agreater advance must be made by the stack after the feeding of one orlmore comparatively thick documents therefrom as compared with theam-ount of advance required after the feeding from the stack of the samenumber of cornparatively thin documents.

This invention utilizes the Well known principle that the frictionalforce exerted by a rst body on a second body, when the two bodies are insliding contact with each other, is proportional to the normal force bywhich the rst body is urged against the second. According to theinvention, an endless member is disposed in the path of advance of astack of documents from which the documents are successively fed. Theendless member provides a friction surface and is driven about a closedpath whereby the frictional force exerted by the foremost document ofthe stack on the driven endless member is proportional to the normalforce by which the foremost document is urged against the endlessmember. This normal yforce is a function of the advance of the stackrequired f prevent over-advancing and under-advancing; it being clearthat no over-advance or under-advance occurs so long as the magnitude ofthis normal force remains within predetermined limits. The resultingfrictional force -being a function of this normal force, thedesiredcontrol ofthe stack advance is achieved according to theinvention by providing means responsive to the magnitude of thisfrictional force to slow-down or st op the stack advance when thisfrictional force exceeds a predetermined value and to speed-up or startthe stack advance when this frictional force becomes less than apredetermined value. According to the disclosed embodiment of theinvention, the endless member is supported, in part, by a supportingmember which is resiliently biased in the direction opposite to thisfrictional force whereby this supporting member tends to deflect in thedirection of the frictional force when the latter increases and tends todeflect in the direction opposite` to that of the frictional force whenthe latter decreases. Means is provided for stopping the stack advancewhen the supporting member deflects past a pre-determined point in thedirection of the frictional force and for starting the stack advancewhen the supporting member delle-cts past a predetermined point in theopposite direction, thereby regulating the stack advance to preventoveradvancing `and under-advancing.

3,069,157 Patented Dec. 18, 1962 Accordingly, an object of thisinvention is to provide a new and improved apparatus for regulating theadvance of a stack of documents as the latter are successively fed Yfromone end of the stack.

A further object of the invention is to provide such an apparatus whichalso urges each document to a pre-fed position before feeding from thestack.

Another object of this invention is to provide such an apparatus whichis automatic in operation, dependable, simple and economical toconstruct.

Further objects and advantages will become apparent as the descriptionproceeds.

An embodiment of the invention is shown in the accompanying drawingswherein:

FIG. l is a plan view, broken away in part, of a document-feeding andstack-advancing apparatus embodying the invention;

FIG. 2 is a schematic Wiring diagram for the stackadvancing controlmeans accordingto this embodiment;

FIG. 3 is a fragmentary plan view, partly in section and on a scaleenlarged over that of FIG. l, showing details of the document-feedingmeans and the stackadvancing control means;

FIG. 4 is a fragmentary front sectional view taken along lines 4 4 inFIG. 3;

FIG. 5 is a fragmentary side sectional View along line S-S in FIG. l;

FIG. 6 is a fragmentary side sectional view taken along line 6--6 inFIG. l and showing a portion of the drive transmission for thedocument-feeding means and the stack-advancing control means, thisportion including a pair of meshing bevel gears;

FIG. 7 is a fragmentary `side sectional View taken along line 7--7 inFIG. l;

FIG. 8 is a fragmentary plan view partly in section of a clutchmechanism through which the stack-advancing means is driven;

FIG. 9 is a fragmentary plan view of a portion o-f the clutch mechanismof FIG. 8, this portion being shown in full in FIG. 9; and

FIG. 10 is a fragmentary front sectional view taken along line 10-10 inFIG. l.

Referring particularly to FIG. l, the disclosed embodiment of theinvention includes a document-feeding means, a stack-advancing means,and a stack-advancing control means generally designated at 20, 22 and24, respectively. Documents, in this case pieces of letter mail, arestacked on edge on a plurality of endless advancing belts 26 of thestack advancing means 22. Although the articles operated upon by theapparatus of the invention will hereinafter be referred to as letters,it will be clear that other documents such as cards, sheets of paper,etc. are fully capable of being so operated upon. The stack of lettersis advanced forwardly (upwardly as viewed in FIG. l) by belts 26 vtobring the foremost letter of the stack into engagement with the outerperiphery of a pair of intermittently movable, endless feed belts 28, 28of the feeding means 20. The outer periphery of feed belts 28, 28 isformed of a frictional material. Each of the feed belts 28, 28 isprovided with at least one series of spaced holes 30 which, when thebelts are in a rest position between feeding intervals of the feedingmeans 20, are disposed rearwardly (to the left as viewed in FIG. 3) of avacuum shoe 32. As feed belts 28, 28 move in the direction of the .arrowin FIG. 3, holes 30 move past the vacuum shoe 32 and communicate withthe hollow interior thereof. Vacuum shoe 32 is mounted on a table 34 andis connected to a suitable vacuum source (not shown) through a hollowconduit 36 as shown in FIG. 4. During operation, a negative pressure isconstantly maintained within the vacuum shoe 32. Consequently, whenthe'uforemost letter of the stackv taken engages feed belts 28, 28, andthe holes move into alignment with the vacuum shoe 32, the foremostletter is retained against, and forwardly fed by these feed belts.

Feed belts 2S, 28 are intermittently movable about a closed path definedby three pairs of supporting pulley wheels 38, 38, 40, and 42, 42.Pulley wheels 42, 42 are xedly carried by a shaft 44 drivenintermittently in the counterclockwise direction as viewed in FIG. 1.Idler pulley wheels 38, 38 are rotatably supported by a shaft 46 tixedlymounted on table 34. Each of idler pulley wheels 40, 40 is supported bya separate stub shaft 48. Each time shaft 44 and pulley wheels 42, 42are driven in said counterclockwise direction, the lower reach of feedbelts 28, 28 (as viewed in FIG. 1) feeds the foremost letter retainedthereagainst to the right (again as viewed in FIG. l) past a frictionseparator 58 and into the bite between an idler take-away roller 52 anda pair of continuously driven take-away belts 54. Friction separator S0is covered with a friction material such as rubber and is supported in aconventional manner by means not shown for yieldable urging toward feedbelts 28, 218. When the foremost letter of the stack is fed by feedbelts 28, 28, the latter retain the foremost letter thereagainst withsufficient force to overcome the frictional force exerted by separator50, but any additional letters carried along with the foremost letterwill be prevented by the separator from being fed to takeaway roller 52and take-away belts 54, 54. In this manner, feeding of the letters fromthe stack in one-by-one succession is ensured. A side wall 56 of thestackadvancing means prevents more than a very few letters from beingcarried with the fed foremost letter to the friction separator.

Idler take-away roller 52 is rotatably mounted on a shaft 58, the latterbeing carried by an L-shaped guide 60. As can be seen in FIG. 1, one endof a tension spring 62 is connected to the shorter leg of the guide 60and the other end of this spring is lixed to table 34. In this manner,the longer leg of the guide and idler take-away roller 52 are yieldablyurged upwardly as viewed in FIG. l. The distal end of the longer leg ofguide 68 diverges away from feed belts 28, 28 to guide the leading endof the fed letters into the bite between belts 28, 28 and separator 50.

Endless take-away belts 54, 54 are supported by pulley wheels 64 and 66.Pulley wheels 64 are rotatably supported by a shaft 68 carried by table34 in a manner identical to that of pulley wheels 38. Pulley wheels 66are fixed on a shaft 70 rotatably supported by table 34 in a manneridentical to that of pulley wheels 42.

The drive for feed belts 28, 28 and take-away belts 54, 54 originateswith a continuously running electric motor 72 whose shaft 74 drives apulley wheel 76 as shown in FIGS. 1 and 10. An endless belt 78 is drivenby pulley wheel 76 and drives a pulley wheel 80 fixed on a shaft 82.Shaft 82 is rotatably supported by table 34- and iixedly carries twoadditional pulley wheels 84 and 86. An endless belt 88 driven by pulleyWheel 84 drives .a pulley wheel 9) xed on a shaft 92. Shaft 92, as shownin FIG. 6, carries a bevel gear 94 in mesh with another bevel gear 96carried by a shaft 98. Shaft 98 xedly carries two pulley wheels 100 and102. Pulley wheel 102 drives an endless belt 104 in turn to drive apulley wheel xed on shaft 70. This pulley wheel driven by belt 104cannot be seen in FIG. l but is identical to pulley wheels 66 and isdisposed directly below the latter. In this manner, the pulley wheels 66are driven to drive take-away belts 54, 54, thereby completing the driveto the latter from motor 72.

Referring to FIGS. l and 10, the pulley wheel 86 drives an endless belt106 in turn to drive a pulley wheel 108 fixed on the input shaft 110 ofa gear box 112. Gear box 112, in a -conventional manner, includesreduction gearing (not shown) to drive .a first output shaft 114 and todrive a Geneva gear arrangement (not shown) for intermittently driving asecond output, one-revolution shaft 116. Fixed to one-revolution shaft116 is a hub 118 threadedly engaged by a pair of headed screws 120 whichextend through arcuate elongated slots 122 provided by a cam 124. Byturning cam 124 about shaft 116 and then tightening down screws 120,120, angular adjustment of the cam about shaft 116 is effected. Thefunction of cam 124 will be set forth later in this description.

A pulley wheel 126 is adjustably secured to shaft 116 below table 34 ina manner identical to that by which cam 124 is secured to shaft 116above the table. An endless belt 12S is supported below the table 34 bythe pulley wheel 126 and by pulley wheels 130 and 132. Pulley wheel 138is xed on shaft 44 as shown in FIG. 7. Pulley wheel 132 is rotatablymounted on a shaft 134 carried by a bracket 136 angularly adjustableabout a bearing support 138 for the shaft 44 as best shown in FIGS. 1and 7. In this manner, the drive from motor 72 to the pulley wheels 42,42 and feed belts 28, 28 is completed.

The drive for the stack-advancing belts 26 of the stackadvancing unit 22will now be described. Referring to FIG. l, the output shaft 114 of gearbox 112 drives a shaft 140 through a universal joint 142. Shaft 140drives the input shaft 144 of a gear box 146 through a universal joint148. With reference to FIG. 8, the input shaft 144 of gear box 146 is.also the input shaft of a clutch disposed within this gear box andgenerally designated at 150. Input shaft 144 is rotatably mounted inbearings 152, 152 carried by brackets 154, 154. A hollow output shaft156 of the clutch 150 has a gear 158 fixed thereon which meshes with agear 168 mounted on a shaft 162 supported within the gear box 146 by aside wall 164. Gear 160, through conventional reduction gearingcontained within gear box 146 and which is not shown, drives anidentically mounted gear 166.

Gear 166 meshes with and drives a gear 168 xed on a shaft 170. Referringto FIG. 1 along with FIG. 5. shaft 170 is rotatably supported by table34 and fixedly mounts four pulley wheels 172. Each of the endlessadvancing belts 26 is trained about one of the pulley wheels 172 andabout one of four pulley wheels 174 at the other end of the stackadvancing means 22. Pulley wheels 174 are supported on a shaft 176 in a`manner identical to that by which pulley wheels 172 are mounted on shaft170. It will be seen that when clutch 150 is engaged, the upper reachesof advancing belts 26 are moved forwardly to advance the stack ofletters toward the feed belts 28, 28. When clutch 158 is disengaged,forward movement of belts 26 and advancing of the stack of letters isstopped.

Referring to FIGS. 5, 8 and 9, the input shaft 144 of clutch 158 isdriven in the clockwise direction (as viewed in FIG. 5) from the gearbox 112 Input shaft 144 is pinned at 177 to a sleeve 178. Hollow outputshaft 156 of the clutch 150 is supported by two anti-friction members180, 182 about input shaft 144 and in alignment with sleeve 178. A coilspring 184 extends from one end 186,. in the counterclockwise direction(as viewed in FIG. 5) about adjacent portions of sleeve 178 and hollowshaft 156, and terminates at the other end 188. When the clutch 150 isengaged, said clockwise rotation of input shaft 144 tightens the turnsof coil spring 184 about sleeve 178 and output shaft 156 to clutch inputshaft 144 and output shaft 156 together. To disengage the clutch, abraking sleeve is disposed in surrounding relation to coil spring 184and provides a slot 192 through which the end 186 of this coil springprojects. So long as braking sleeve 190 is free to rotate with inputshaft 144, no -braking effect is exerted thereby. By forcibly stoppingrotation of braking sleeve 190, the end 186 of coil spring 184 engagesand is stopped from rotating by one side of slot 192 thereby opening orloosening the turns of this coil spring about sleeve 178 and outputshaft 156. The

effect is to de-clutch output shaft 156 from input shaft 144 whereby theclutch 150 is disengaged.

To forcibly stop rota-tion of braking sleeve 190i, a flexible wire 194is Wrapped about the braking sleeve and terminates at one end which issecured at 195 to a circular plate 196 retained in rotatably adjustedposition by a plurality of screws 197 tightened in threaded engagementwith a side wall 199 of the gear box 146. The other end of flexible wire194 is secured to a link 198, the latter being urged to the right (asviewed in FIG. 5) by a tension spring 200. Spring 200 is attached to abracket 2012 provided by the gear box 146. Link 19S is secured to aplunger 204 operated by a solenoid 266. Spring 200 is effective totighten the coils of wire 194 about braking sleeve 180 forcibly toprevent rotation of the braking sleeve thereby to maintain the clutch150 in disengaged condition. When solenoid 206 is energized, link 198 ispulled to the left (as viewed in FIGS. 5 and 8) to loosen the coils ofwire 194 about braking sleevelStl ythereby to cause engagement of theclutch 150. Clutch 150 is therefore normally disengaged and is engagedby energizing solenoid 206.

The control means 24 by which the stack-advancing means 22 is regulatedwill now be described. Referring to FIGS. 1 and 3-5, this control means24 includes an endless belt 210 supported for movement about a closedpath by pulley wheels 212 and 214. Pulley wheel 212 is supported forrotation about a stub shaft 216 by a bracket arm 218, and bracket arm218 as well as pulley wheel 214 is supported for rotation about a shaft220. Shaft 220, as can best be seen in FIG. 5, is fixedly supported by amounting plate 222 secured to table 34. In this manner, pulleyV wheel212 is supported for pivotal deflection in opposite directions about theaxis of shaft 220.

Endless belt 210 is formed of a material such as rubber providing anouter friction surface. Pulley wheel 2-12 is disposed at a level betweenfeed belts 28, 28 so as to support endless belt 210 with a portionextending beyond the feed belts 28, 28 as best shown in FIGS. 3 and 5.Accordingly, a portion of the radially outer frictional surface of belt210 is disposed in the path of advance of the stack for engagement bythe foremost letter of the stack.

Referring particularly to FIG. 5, pulley wheel 214 is integral with acylindrical section 224 and with a pulley wheel 226. An endless belt 228drives pulley wheel 226 in the counterclockwise direction (as viewed inFIG. 3)

and is driven by the pulley Wheel 100 secured to shaft 98 (see FIG. 6).Shaft 98 is driven -by motor 72 through transmission means previouslydescribed. In this manner, endless belt 210 of the stack-advancingcontrol means' 24 is continuously driven in the counterclockwisedirection (as viewed in FIGS. l and 3).

It will be apparent that since endless belt 210 is continuously drivenin saidcounterclockwise direction, any force exerted by the foremost'letter of the'stack against the friction surface of belt 210 in thedirectionV of the ad vanc'e of the stack tends to cause deection ofpulley wheel 212 and the portion of belt 210`engaged thereby to the left(as viewed in FIGS. l and 3). This is due to the frictional forcebetween the foremost letter of the stack and the frictionl surface ofbelt 21,0. The magnitude of this frictional force is a function ofthenormal force exerted by the foremost letter of the stack against lthefriction surface of belt 210. This conforms, of course, to the wellknown principle that the'frictional force exerted by a first body on asecond body, when the two bodies are in sliding contact with each other,is directly proportional to the normal force by whichthe first body isurged against the second.

A rearward extension of bracket 2148 iixedly carries an arm 230. Theydistal end of arm 230 supports a paddle 232 which extends into aquantity of viscous oil 234 disposed in a container 236. The top 238 ofcontainer 234 provides afslot 240 through which paddle 232 extends.`:This -arrangement actsto dampen the sensitivity of the stack-advancingcontrol means 24 whereby this controlv means is responsive only tosignificant changes in force exerted against endless belt 210. l

The top 238 of container 236 mounts a block 242 which threadedlyreceives an adjusting screw 244. Screw 244 acts as a stop engageablewith a button 246 carried by arm 230 to define the limit of pivotaldeflection of arm 23@ and belt 210 in the counterclockwise directionabout shaft 220 (as viewed in FIG. 3). Screw 244 is secured in adjustedposition by tightening down a lock-nut 248. In identical fashion anadjusting screw 250 limits the pivotal deflection of arm 230 and belt210 in the clockwise direction about shaft 220. A tension spring 252 isconnected at one end to arm 230 and at its other end to a bracket 254supported by container top 238 whereby arm 234.) is resiliently biasedin the counterclockwise direction to the position of engagement withscrew 244 as shown in FIG. 3. Upon clockwise deflection of arm 23)'against the bias of spring 252, one end of an adjusting screw 256depresses an actuating member 258 of a normally-closed electrical switch260 to open the latter. Adjusting screw 256 is in threaded engagementwith arm 23@ and is secured in adjusted position by tightening a locknut 262. It will be clear, then, that when the stack of letters hasforwardly advanced sufficiently that the frictional force between theendless belt 216 and the foremost letter of the stack is great enough tocause the pulley wheel 212 and the portion of belt 210 engaged by theforemost letter to deflect to the left against the action of spring 252(as viewed in FIGS. l and 3) and etfect actuation of switch 260, thelatter will be opened. The opening of switch 260` results indisengagement of the clutch (FIGS. 5, 8 and 9) to stop the forwardmovement of stack-advancing belts 26. As letters are fed from the stack,this frictional force decreases to the point .that pulley wheel 212 andthe engaged portion of belt 21) deiiect to the right under the action ofspring 252 to effect closing 4of switch 269. The closing of switch 26)`results in engagement of the clutch 150 to start the forward movement ofstack-advancing belts 26. By appropriate selection -of thecharacteristics of spring 252, the advance of the stack will beregulated by the control means 24 to keep the respective foremost letterof the stack in proper position to be fed by the feed belts 28, 28(i.e., to prevent over-advancing and underadvancing of the stack by thestack-advancing means 22).

The use of the control belt 210 has the advantage over afriction-material covered roller substantially equal in size to thepulley wheel 212 that wear is more greatly distributed over the greaterouter surface of the belt 210. Y

The stack-advancing control means 24 as described thus far is operativewhether Vthe feed of the letters while in contact with the endless belt210 of this control 4means is intermittent (as is the case with feedingmeans 20 as described herein) or continuous, and whether this feed is atvariable speed (as with feeding means 20 due tothe previously mentionedGeneva gear arrangement) or at constant speed. This is the case becausethe previously noted principle to the effect that the frictional forcebetween two relatively sliding bodies is directly proportional to thenormal force therebetween, remains true regardless of changes in therate or speed of relative sliding between the two bodies (see, forexample, page 75 of the book Analytic Mechanics by Chambers and Faires,published by The MacMillan Co., 1949). However, a given installation towhich the invention is applied may present effects making it desirablethat the stack-advancing control means be blanked outr (.i.e. renderedineffective) periodically. By way of example, the endless belt 21d# ofstack-advancing control means 24 is continuously driven about its closedpath in the direction such that the portion of this beltthat engages theforemost letter of the stack defiects in the same direction vas the feedofthe foremost letterfrom the stack.

If, for any reason, endless belt l218 is driven at a pe ripheral speedslower than the maximum speed attained by the respective foremost letter(While the latter is being fed in contact with the former), it will beclear that the direction of relative movement between this endless beltand the foremost letter will be reversed as the foremost letter reachesand then exceeds the peripheral speed of the endless belt. The resultwould be to cause counterclockwise rather than clockwise pivotaldeflection of pulley wheel 212 and the engaged portion of endless belt216 with an increase in said frictional force, thereby falselyindicating that the stack should be advanced. This result could beavoided, for example, by rotatably driving endless belt 210 in theopposite direc-tion from that described herein or by driving endlessbelt 219 at a peripheral speed exceeding the maximum feeding of therespective foremost letter while in contact with this belt. Otherfactors may prevail, however, militating against such modifications andfavoring periodic blankingout of the stack-advancing control means 22when such false indications may or do occur. Another effect that mayoccur rendering it desirable to blank-out the control mechanismperiodically would be that resulting when the periodically applied forceby which the foremost letter is retained against the feed belts 28, 28under the influence of the negative pressure within vacuum shoe 32causes an undue increase in the normal force by which the foremostletter of the stack is urged against the endless belt Zi such as mightupset the action of the control means 24. To accommodate these and/ orany other such factors, the electrical circuitry of the stack-advancingcontrol means 24 is arranged, as will now be described.

Referring to the schematic wiring diagram of FIG. 2, switch 260 and theclutch-operating solenoid 206 along with the normally closed switch 264of a relay generally designated at 266 are electrically connected inseries relation across a line source of current. Accordingly, whenevera-t least one of switches 268 and 264 opens, solenoid 286 isde-energized to effect disengagement of clutch 150 resulting in stoppingof the forward movement of the stack-advancing belts 26 to stop theadvance of the stack.

As previously explained, opening of switch 26) indica-tes that advancingof the stack is to be stopped by deenergization of solenoid 286 toprevent an over-advance of the stack. Opening of relay switch 264,however, deenergizes solenoid 206 to stop the advance of the stackregardless of whether switch 268 is open or closed, thereby to blank-outthe stack-advancing control means 24. To accomplish the latter, a switch268 (FIG. l) is arranged to be opened during each cycle of the feedingmeans. In this regard, switch 268 is carried by a bracket 270 mounted ongear box 112 to dispose an actuator 272 of this switch in the path ofthe large-diameter portion of the previously mentioned cam 124. As hasbeen noted, cam 124 is fixed, along with the pulley wheel 126 whichultimately drives feed belts 28, on one-revolution shaft 116.Accordingly, each time shaft 116 rotates its one revolution, thelarge-diameter portion of cam 124 rides against actuator 272 to closeswitch 268 and then past this actuator to open the switch 268. Referringagain to the schematic wiring diagram of FIG. 2, the normally-openelectrical switch 268 is electrically connected in series relation withthe coil of relay 266 across the line source of current. When switch 268is closed, relay 266 picks up to open switch 264 resulting inde-energization of solenoid 286 and stopping of the stack-advancingbelts 26. In this manner, stack-advancing control means 24 isblanked-out during a portion of each feeding cycle so that no forwardmovement of advancing belts 26 occurs during this portion of the letterfeed even though switch 268 may be closed to demand such forwardmovement of the advancing belts 26.

It was found desirable, with the feeding means 20 as described above, toblank-out the stack-advancing control means for a short time beyond thepoint at which the actuator 272 of switch 263 is released by cam 124 tothe switch-open position. Referring to FIG. 2, this was accomplished ina conventional manner by electrically connecting a resistor 274 and acondenser 276 in series relation with each other across the terminals ofrelay 266. This operates to provide a proper time-delay betweenreopening of switch 268 and drop-out of the relay. In this regard,condenser 276 charges when switch 268 is closed, and then dischargesthrough the coil of relay 266 when switch 268 re-opens, to delay thedrop-out of the relay. The desired length of time delay is achieved byselecting a resistor 274 and condenser 276 of the proper electricalparameters.

One reason why pulley wheel 212 and endless belt 210 are driven in thecounterclockwise direction (as viewed in FIGS. l and 3) rather than inthe opposite or clockwise direction as previously suggested, is that,thereby, belt 216 acts not only as a part of the stack-advancing controlmeans but also as a pre-feeder. In this regard, by driving endless belt210 in said counterclockwise direction, the portion of this belt incontact with the respective foremost letter of the stack moves in thedirection of thel feed of the successive letters from the stack. Aspreviously noted, at the rest position of feed belts 28, 28, holes 30therein are disposed short of vacuum shoe 32 so that the only force bywhich the respective foremost letter of the stack is urged against thebelt 218 is that effected by the advance of the stack. Consequently,each successive foremost letter is substantially free to be pre-fed bythe continuously driven belt 210 into the bite between frictionseparator Si) and feed belts 28, 28 just prior to feeding by the feedbelts 28, 28. This pre-feeding feature is advantageous among otherreasons, because, thereby, each letter is fed by the feed belts 28, 28from a registered (prefed) position regardless of whether or not theletters in the stack are registered against the side wall 56 of thestack-advancing means 22 during advancing of the stack.

In connection with the stacloadvancing means 22, the letters of thestack are supported in upright position at the rear of the stack bymeans of a movable support 280 as shown in FIG. l. Support 280 iscarried at one end by a sleeve 282 which is freely slidable andpivotable on and about a bar 284 of circular cross-section. Bar 284extends the length of stack-advancing unit 22. Support 280 has a rubberor other friction-material pad 286 secured to its underside andengageable with one of the advancing belts 26. In operation, support 280is pivoted upwardly about bar 284 to disengage friction pad 286 from therespective advancing belt 26, a stack of letters is disposed on thebelts 26, support 288 is moved longitudinally relative to bar 284 to apoint just behind the last letter of the stack, and the support is thenpivoted downwardly about bar 284 to engage friction pad 286 with therespective advancing belt 26. By virtue of the frictional contact of thepad 286 with the respective advancing belt 26, along with the slidingconnection between sleeve 282 and bar 284, support 280 is advancedagainst the rear of the stack along with advancement of the stack by theadvance of belts 26 whereby the upright condition of the letters of thestack is maintained.

Referring to FIG. 5, the surface of the stack-advancing unit 22 on whichthe letters of the stack advance next adjacent feed belts 28, 28 andcontrol belt 210, is inclined upwardly at 288 and then more sharplydownwardly at 290. As will be clear, this has the effect of causing theletters at the forward end portion of the stack to remain upright in theproper altitude for engagement with belts 28, 28 and 210` rather than toincline rearwardly from their lower edges.

With the exception of the advancing belts 26 and the drive belt 228,each of the endless belts described above is a so-called timing belthaving ribs or teeth meshing with either two or three toothed pulleywheels. Take-up means is provided where desired to tension certain ofthe belts. Referring particularly to FIG. 3 in this regard, the upperone of the two pulley wheels 40 about which a respective feed belt 28 istrained is carried by its stub shaft 48 mounted at the free end of oneleg 292 of an integral two-legged bracket generally designated at 294.The lower one of the two pulley wheels 40 is carried by its stub shaft48 mounted at the free end of one leg identical to leg 292 and integralwith a three-legged bracket generally indicated at 296. Both of brackets294 and 296 are pivoted about a pin 298 fixed to table 34. A second leg300 of bracket 296 is secured in adjusted pivotal position about pin 298by tightening down a bolt 302 whose shank extends through a slot 304provided by leg 300 and into threaded engagement with a block 306secured to table 34. This adjustment, of course, properly tensions thelower one of feed belts 28. A third leg 308 of bracket 296 rotatablysupports an adjusting screw 310 threadedly received by a second leg 312yof bracket 294. Bracket 294 is pivotally adjusted about pin 298 andrelative to bracket 296 by rotating screw 310. By tightening down alock-nut 314, the upper one of feed belts 28 is maintained in propertension.

The drive belt 228 is tensioned by an idler roller 316 (FIG. l)rotatable about a shaft 318 carried by a bracket 320. The desiredtension on belt 228 is achieved by moving bracket 320 in the directionstoward or away from belt 228 and securing this bracket in adjustedposition by tightening down screws 322 which extend in threadedengagement with table 34 through slot 324. An idler roller .326 isutilized to adjust the tension on drive belt 104 in a manner identicalto that by which the tension on belt 228 is adjusted by roller 316. Thetension on belt 104 is adjusted after adjusting the tension on take-awaybelts 54. The latter is accomplished by adjustably pivoting a bracket328, which carries the shaft 70 for pulley wheels 66, about a pin 330secured to table 34, and then tightening down a screw 332 which extendsthrough a slot in bracket 328 into threaded engagement with table 34.

Briefly to recapitulate the operation of the disclosed appara-tus, astack of letters is advanced endwise toward and against the -feed belts28, 28 and the stack-advancing control belt 210 by forward movement ofthe advancing belts 26. Advancing belts 26 are moved forwardly when theclutch 150 (FIGS. 5 and 18) is engaged, and forward movement of theseadvancing belts is stopped when the clutch 150 is disengaged. Referringto the schematic wiring diagram of FIG. 2, the clutch 150 is engagedwhen the solenoid 206 (FIGS. 5 and 8) is energized and is disengagedwhen this solenoid is de-energized. The solenoid 206 is de-energizedwhen the switch 260 is open and, so long as switch 264 of relay 266 isclosed, the solenoid 206 is energized when the switch 260 is closed.Assuming that switches 260 and 264 are closed to energize solenoid 2016to engage clutch 150 to drive advancing belts 26 and a stack of lettersthereon forwardly, the frictional force exerted by the foremost letterof the stack against the continuously driven stack-advancing controlbelt 210 increases as a function of the increase of the normal forceexerted by said-foremost letter against the control bel-t 210. When thisfrictional force exceeds a predetermined value, pulley wheel 212, andthe portion of control belt 210 engaged by the foremost letter pivot inthe clockwise direction (as viewed in FIGS. 1 and 5) substantiallyperpendicular to the direction of advance of the stack the small amountrequired to cause arm 230 to open switch 260 thereby stopping theforward advance of the stack by the stack-advancing means. Thefrictional force exerted -by the respective foremost letter of the stackagainst the engaged portion of the control belt 210 decreases as theletters are successively fed from the stack to a predetermined value atwhich the pulley wheel 212, the engaged portion of the control belt 210and arm 230 pivot under the influence of the spring 252 in thecounterclockwise direction the small amount required to effect closingof switch 260 again to start forward advancing of the ad- 10 vancingbelts26. The switch 268' is provided if and when it is desired toenergize relay 266 to open relay switch 264 periodically during eachletter feeding cycle to blank-- out the stack-advancing control means24.

It will be noted that the .'force necessary to be exerted by control arm230 to open switch 260 of the stack-advancing control means 24, isdetermined (along with other factors such as the friction of thebearings which pivotally support bracket 213 about shaft 220, etc.) bythe cumulative force of spring252 and the conventional return spring(within the casing of switch 260 and which is not shown) for theactuator 258 of this switch. By the proper selection of a conventionalactuator return spring to provide a force equal to this cumulativeforce, spring 252 could be elimina-ted. Also, rather than a start-stopcontrol over the forward movement of advancing belts 26 as hereindescribed, this forward movement could be regulated by a variable-speedmechanism responsive to the pivotal position of pulley wheel 212 and theportion of control belt 210 engaged lby the respective foremost letterof the stack since the amount of this pivotal movement is a function ofthe required advance of the stack.

The particular feeding, stack-advancing and control apparatus disclosedherein forms part of an input station for a letter sorter machine but itwill be obvious that the invention is applicable to many otherinstallations. Furthermore, since many changes can be made in the lembodiment of the invention as particularly described and shown hereinwithout departing from the scope of the invention, it is intended thatthis embodiment be considered as exemplary and that the invention not belimited except as warranted by the following claims.

What is claimed is:

1. In an apparatus for feeding letters in succession from a stack; meansfor advancing the stack endwise as the letters are fed therefrom; anendless member having a continuous friction surface; means -supportingsaid endless friction-surfaced member for movement about a closed path;said supporting means including a member supporting a portion of saidendless member in the path of advance of the stack of letters forengagement of the friction surface of said portion of the endless memberwith the foremost letter of the stack; means operatively `connected fordriving said endless member about a closed path; means mounting saidsupporting member for deflection in opposite directions substantiallyperpendicular to the direction of advance of the stack of letters; meansresiliently biasing said supporting member in one of said oppositedirections against any force exerted on said friction surface in theother one of said opposite directions by the foremost letter of saidstack whereby said supporting member tends to deflect in said one of theopposite directions with a decrease in said force and tends to deflectin said other one of the opposite directions with an increase in saidforce; and means operatively connected to said stack-advancing means andresponsive to the deflection of said supporting member in said oppositedirections to regulate the advance of said stack by said stack-advancingmeans.

2. In an apparatus for feeding letters in succession from a stack; meansfor advancing said stack of letters endwise as the letters are fedtherefrom; al friction separator disposed at a pre-fed position; anendless member having a xfriction surface disposed in the path ofadvance of said stack to engage the foremost letter of the stack; meansoperatively connected to drive said endless friction surlface about aclosed path and in a direction to frictionaily urge the foremost letterof the stack to said pre-fed position against said friction separator;means mounting said endless friction-surfaced member for deflection ofthe portion of said endless member engaged by said foremost letter inopposite directions substantially perpendicular to the direction ofadvance of said stack and resiliently biasing said friction-surfacedmember in one of said opposite directions against any frictional forceexerted on the endless friction-surfaced member by the foremost letterof said stack whereby said friction-surfaced member tends to deflect insaid one of the opposite directions with a decrease in said frictionalforce and tends to deflect in said other one of the opposite directionswith an increase in said frictional force, and means responsive to thedeflection of said friction-surfaced member in said opposite directionsto regulate the advance of said stack.

3. In combination: means for feeding letters in oneby-one successionfrom a stack; an end-less belt having a friction surface; means foradvancing a stack of letters in a direction toward said endless belt;means supporting said endless belt for movement about a closed path;said supporting means including a pulley wheel supporting a portion ofsaid belt in the path of advance of the stack of letters for engagementof the friction surface of the belt with the foremost letter of thestack; means operatively connected for driving said endless belt about aclosed path; means mounting said pulley wheel for deflection in oppositedirections substantially perpendicular to the direction of advance ofthe stack of letters; means resiliently biasing said pulley wheel in oneof said opposite directions against any force exerted on saidfriction'surface in the other one of said opposite directions by theforemost letter of said stack whereby said pulley wheel tends to deflectin said one of the opposite directions with a decrease in said force andtends to deflect in said other one of the opposite directions with anincrease in said force; and means responsive to the deflection of saidpulley wheel in said opposite directions to regulate the advance of saidstack by said stack-advancing means as the letters are fed therefrom.

4. In an apparatus for feeding letters in succession from a stack;means, when actuated, for advancing the stack endwise as the letters arefed therefrom; an endless member having a continuous friction surface;means Supporting said endless friction-surfaced member for movementabout a closed path; said supporting means including a member supportinga portion of said endless member in the path of advance of the stack ofletters for engagement of the friction surface of the endless memberwith the foremost letter of the stack; means operatively connected fordriving said endless member about a closed path; means mounting saidsupporting member for deflection between two positions and substantiallyperpendicular to the direction of advance of the stack; meansresiliently biasing said supporting member with a predetermined forcefrom one of said positions to the other position; an electrical switchoperatively arranged to be actuated by deflection of said supportingmember from said other position to said one position when the frictionalforce exerted by the foremost letter of the stack against said endlessmember exceeds said predetermined force, and means electricallyconnected to said switch for de-actuating said first-named means so longas said switch is actuated.

5. In an apparatus for feeding letters in succession from va stack;means, when actuated, for advancing said stack of letters endwise as theletters are fed therefrom; 'an endless member having a continuousfriction surface; means supporting said endless friction-surfaced memberfor movement about a closed path; said supporting means including amember supporting a portion of said endless member in the path ofadvance of the stack of letters for engagement of the friction surfaceof the endless member with the foremost letter of the stack; meansoperatively connected for driving said endless member about a closedpath; means mounting said supporting member for deflection between twopositions and substantially perpendicular to the direction of advance ofthe stack; means resiliently biasing said supporting member with apredetermined force from one of said positions to the other position; afirst electrical switch operatively arranged to be actuated bydeflection of said supporting member from said other position to saidone position when the frictional force exerted by the foremost letter ofthe stack against said endless member eX- ceeds said predeterminedforce; a second electrical switch operatively arranged to be actuatedduring the time interval while each letter being fed from the stackengages the the friction surface of the endless member; and meanselectrically connected to both of said electrical switches forde-energlzing said first-named means so long as either one or both ofsaid electrical switches is actuated.

6. In an apparatus for feeding letters in succession from a stack; meansfor advancing said stack of letters endwise as the letters are fedtherefrom; an endless member; means supporting said endless member inthe path of advance of said stack; said endless member providing acontinuous friction surface engageable with the respective foremostletter of the stack; means operatively connected for continuouslydriving said endless member to move said continuous friction surfaceabout a closed path whereby the resulting frictional force between said'friction surface and the respective foremost letter of the stack isproportional to the normal force therebetween; said supporting meansincluding a member mounted for deflection in response to changes in saidfrictional force; the deflection of said last-named member beingproportional to said frictional force; and means responsive to saiddeflection of said last-named member and operaive'y connected forcontrolling said stack-advancing means to maintain said deflectionwithin predetermined limits whereby over-advancing and under-advancingof said stack are prevented.

References Cited in the ille of this patent UNITED STATES PATENTS2,660,430 Ribich Nov. 24, 1953 2,956,801 Coakley Oct. 18, 1960 2,992,820Tarbuck et al. July 18, 1961

